Drive method of el display apparatus

• US 7,742,019 B2
• Filed: 03/06/2003
• Issued: 06/22/2010
• Est. Priority Date: 04/26/2002
• Status: Active Grant

• Current Assignee: Japan Display Central Incorporated (Japan Display Incorporated)
• Original Assignee: Toshiba Matsushita Display Technology (Japan Display Incorporated)
• Inventors: Takahara, Hiroshi
• Primary Examiner(s): Shalwala; Bipin
• Assistant Examiner(s): Chowdhury; Afroza Y
• Application Number:
  US10/511,437
• Publication Number:
  US 20050168490A1
• Time in Patent Office: 2,665 Days
• Field of Search: 345/690, 345/76
• US Class Current: 345/76
• CPC Class Codes: G09G 2300/0452 Details of colour pixel setup, e.g. pixel composed of a red, a blue and two green components
• CPC Class Codes: G09G 2300/0842 forming a memory circuit, e.g. a dynamic memory with one capacitor
• CPC Class Codes: G09G 2300/0861 with additional control of the display period without amending the charge stored in a pixel memory, e.g. by means of additional select electrodes
• CPC Class Codes: G09G 2310/0235 Field-sequential colour display
• CPC Class Codes: G09G 2310/0248 Precharge or discharge of column electrodes before or after applying exact column voltages
• CPC Class Codes: G09G 2310/0251 Precharge or discharge of pixel before applying new pixel voltage
• CPC Class Codes: G09G 2310/0297 Special arrangements with multiplexing or demultiplexing of display data in the drivers for data electrodes, in a pre-processing circuitry delivering display data to said drivers or in the matrix panel, e.g. multiplexing plural data signals to one D/A converter or demultiplexing the D/A converter output to multiple columns
• CPC Class Codes: G09G 2320/0247 Flicker reduction other than flicker reduction circuits used for single beam cathode-ray tubes
• CPC Class Codes: G09G 2320/0261 in the context of movement of objects on the screen or movement of the observer relative to the screen
• CPC Class Codes: G09G 2320/0271 Adjustment of the gradation levels within the range of the gradation scale, e.g. by redistribution or clipping
• CPC Class Codes: G09G 2320/0276 for the purpose of adaptation to the characteristics of a display device, i.e. gamma correction
• CPC Class Codes: G09G 2320/064 by time modulation of the brightness of the illumination source
• CPC Class Codes: G09G 2320/066 for control of contrast
• CPC Class Codes: G09G 2330/021 Power management, e.g. power saving
• CPC Class Codes: G09G 2360/16 Calculation or use of calculated indices related to luminance levels in display data
• CPC Class Codes: G09G 3/2014 by modulation of the duration of a single pulse during which the logic level remains constant
• CPC Class Codes: G09G 3/22 using controlled light sources
• CPC Class Codes: G09G 3/3241 the current through the light-emitting element being set using a data current provided by the data driver, e.g. by using a two-transistor current mirror
• CPC Class Codes: G09G 3/325 the data current flowing through the driving transistor during a setting phase, e.g. by using a switch for connecting the driving transistor to the data driver
• CPC Class Codes: G09G 3/3266 Details of drivers for scan electrodes
• CPC Class Codes: G09G 3/3283 : in which the data driver supplies a variable data current for setting the current through, or the voltage across, the light-emitting elements

Abstract

A drive method of an EL display apparatus that includes a switching element that turns on and off a current path between a driver transistor and an EL element. The drive method aggregates image data input to the EL display apparatus, and determines a period to turn off the switching element according to an amount of the aggregate data. With the method, suppression of peak current and expansion of contrast and so on is realized.

Claims

1. A drive method of an EL display apparatus that comprises a display screen in which a plurality of pixels each of which includes an EL element are formed in a matrix and a switching element which turns on/off a current that flows in the EL element, the drive method comprising:

weighting image data with respect to a color of respective of the plurality of pixels, said image data generating a signal which is to be impressed to the respective pixels of the EL display apparatus,

aggregating said weighted image data, and

when results of said aggregating of said weighted image data are larger than a predetermined value,

suppressing an amount of current that flows in the EL element by shortening a time period to pass the current during one frame period by controlling said switching element, displaying a non-display area on the display screen of the EL display apparatus, and shifting the non-display area on the display screen synchronizing with said one frame period.

3. The drive method of an EL display apparatus according to claim 1, wherein:

said EL display apparatus comprises a gate driver circuit that drives a gate signal line selecting a line of the pixels,

the non-display area is generated in a belt-like form on the display screen of the EL display apparatus by the gate driving circuit driving the gate signal line; and

the non-display area is shifted scanning direction of the gate driver circuit.

4. The drive method of an EL display apparatus according to claim 1, further comprising:

detecting brightness of outside the EL display apparatus;

generating a belt-like non-display area and a belt-like display area; and

changing or adjusting a ratio of the belt-like non-display area and the belt-like display area according to an output value obtained by the detecting.

11. The drive method of an EL display apparatus according to claim 1, wherein:

a driver transistor for supplying current to said EL element is formed in said pixel of said EL display apparatus, and

said driver transistor is a P-channel transistor.

12. The drive method of an EL display apparatus according to claim 1,

wherein, said EL display apparatus further comprises;

a source driver circuit that applies an image signal and,

a switch circuit arranged between an output terminal of said source driver circuit and source signal lines which said pixel is connected with, and

wherein, said switch circuit impresses image signal which is output from said output terminal of said source driver circuit to selected source signal line.

2. An EL display apparatus including a display screen in which a plurality of pixels each of which includes an EL element are formed in a matrix, the EL display apparatus comprising:

a switching element which turns on/off a current that flows in the EL element;

a gate driver circuit that drives a gate signal line selecting a line of the pixels;

an aggregation circuit configured to weight image data with respect to color of respective of the plurality of pixels, said image data generating a signal which is to be impressed to the respective pixels of the EL display apparatus, and to aggregate the weighted image data; and

a control circuit that controls a timing or a period to generate a start pulse signal for the gate driver circuit based on the aggregated image data, wherein

the gate driver circuit drives the gate signal line according to the start pulse signal, generates a non-display area on the display screen by controlling said switching element, and shifts the non-display area in a scanning direction of the gate driver circuit.

5. The EL display apparatus according to claim 2, further comprising:

a selection circuit formed on a substrate on which the EL elements are formed; and

a source driver circuit, wherein

the source driver circuit outputs a video signal of a first color or a video signal of a second color from a signal output terminal,

the substrate includes source signal lines to supply the video signals of the source driver circuit to the EL elements,

the selection circuit includes an input terminal to connect to the signal output terminal of the source driver circuit and a selection output terminal to connect to the source signal line,

the selection circuit includes a plurality of combinations of one output terminal and a plurality of selection output terminals configured to connect to the one output terminal, and

the selection circuit applies a video signal of the source driver circuit input to the input terminal of the selection circuit to the source signal line connected to the one or plural of selection output terminals that are selected from the plurality of the selection output terminals.

6. The EL display apparatus according to claim 2, further comprising

a source driver circuit that applies a gradation signal to the EL elements, wherein

the source driver circuit includes a voltage output circuit and a current output circuit.

7. The EL display apparatus according to claim 2, wherein

brightness of the display screen is controlled by varying a ratio of the non-display area to the display screen.

8. The EL display apparatus according to claim 2, wherein

the shifting the non-display area in the display screen is performed synchronizing with one flame period.

9. The EL display apparatus according to claim 2, wherein

in the display screen, the plurality of pixels having a plurality of colors are formed in a matrix, and

an area of an element of one color of the plurality of colors is different from an area of an element of the other colors.

10. The EL display apparatus according to claim 2, wherein the non-display area is divided into a plurality of parts.

13. The EL display apparatus according to claim 2, wherein:

a driver transistor for supplying current to said EL element is formed in said pixel of said EL display apparatus, and

said driver transistor is a P-channel transistor.

14. The EL display apparatus according to claim 2, further comprising:

a source driver circuit that applies an image signal and,

a switch circuit arranged between an output terminal of said source driver circuit and source signal lines which said pixel is connected with, and

wherein, said switch circuit impresses image signal which is output from said output terminal of said source driver circuit to selected source signal line.